Extravasation detection system and apparatus

Abstract

A system is disclosed for detecting extravasation of injected liquid from the blood vessel of a patient. The system operates by monitoring electromagnetic microwave emission from the patient at the injection site by means of a microwave antenna assembly and processing apparatus connected to the antenna assembly for responding to changes in the microwave emission characteristics representative of extravasation. The antenna assembly has a reusable antenna element connected to the processing apparatus, a disposable attachment element for adhering to the patient's skin, and interfitting male and female coupling formations on the attachment element and the antenna element respectively for releasably coupling the reusable element to the disposable element.

We claim: 
     
       1. A system for microwave detection of extravasation of liquid from a blood vessel of a patient into which the liquid is injected, the system including microwave antenna means for receiving microwave emission signals from the patient and processing means connected with the antenna means for responding to changes in said signals representative of extravasation, the antenna means including a reusable antenna element connected to said processing means, a disposable attachment element for adhering to a patient's skin over an injection site, and interfitting male and female coupling means on the attachment element and the antenna element respectively for releasably securing the antenna element on the attachment element in intimate contact with the patient's skin. 
     
     
       2. A system for microwave detection of extravasation of liquid from a blood vessel of a patient into which the liquid is injected, the system including microwave antenna means for receiving microwave emission signals from the patient and processing means connected with the antenna means for responding to changes in said signals representative of extravasation, the antenna means including a reusable antenna element connected to said processing means, a disposable attachment element for adhering to a patient's skin over an injection site, and interfitting male and female coupling means on the attachment element and the antenna element respectively for releasably securing the antenna element on the attachment element in intimate contact with the patient's skin, wherein the reusable antenna element comprises a conductive outer housing, a conductive launching probe within said housing and a dielectric material within said housing separating the launching probe from the housing, further wherein said female element comprises a recess in the dielectric material and the male element comprises a button of like dielectric material on the attachment element to fit in said recess. 
     
     
       3. The system defined in claim 2, wherein the button comprises a cylindrical larger diameter base portion and a cylindrical smaller diameter upper portion, the upper portion adapted to fit in said recess and the housing of the antenna element having an enlarged skirt portion to receive said base portion of the button. 
     
     
       4. The system defined in claim 2, further including an elongate scale member removably attachable to said button for centering the button relative to a tip of an injection cannula used for injecting liquid into the patient's blood vessel. 
     
     
       5. The system defined in claim 2, wherein the attachment element comprises a flexible carrier film having an adhesive undersurface, the button being located on an upper surface of said carrier film. 
     
     
       6. The system defined in claim 5, wherein the carrier film has a portion surrounding the button with an adhesive upper surface to secure the housing of the antenna element. 
     
     
       7. The system defined in claim 6, further including a sterile envelope enclosing the antenna element with a circular cut-out accommodating a rim portion of said housing and a ring of adhesive around said cut-out. 
     
     
       8. The system defined in claim 6, wherein the carrier film has an extended portion beyond said surrounding portion and the extended portion is covered by a conformal flexible stabilizing layer. 
     
     
       9. The system defined in claim 8, wherein the extended portion has a circular section with at least one radial leg extending outwardly from said circular section. 
     
     
       10. The system defined in claim 9, wherein the leg is provided with a longitudinal scale for centering the button relative to a tip of an injection cannula used for injecting the liquid into the patient's blood vessel. 
     
     
       11. A system for microwave detection of extravasation of liquid from a blood vessel of a patient into which the liquid is injected, the system including microwave antenna means for receiving microwave emission signals form the patient and processing means connected with the antenna means for responding to changes in said signals representative of extravasation, the antenna means including a reusable antenna element connected to said processing means, a disposable attachment element for adhering to a patient's skin over an injection site, and interfitting male and female coupling means on the attachment element and the antenna element respectively for releasably securing the antenna element on the attachment element in intimate contact with the patient's skin, wherein the processing means includes a radiometer connected to the antenna element by a coaxial cable having an inner conductor connected to the launching probe and an outer conductor connected to the housing. 
     
     
       12. The system defined in claim 11, wherein the processing means further includes an injector head for operating a syringe to inject the liquid, and microprocessor means associated with the injector head and operated by signals received from the radiometer to terminate injection responsive to changes in said signals representative of extravasation. 
     
     
       13. A reusable microwave antenna element for receiving microwave radiation from a body of a patient during injection of liquid into a blood vessel, by attachment of the antenna element in intimate contact with skin of the patient, comprising an outer cup-like conductive housing with a rim for securing in intimate contact with the skin, a conductive launching probe leading into said housing, a dielectric material filling the housing and separating the launching probe from the housing, and a recess in the dielectric material for receiving part of a button of like dielectric material on an attachment element used for securing the antenna element to the patient's skin. 
     
     
       14. An antenna element as claimed in claim 13, wherein the housing has an enlarged skirt portion under the dielectric material to receive a base portion of a dielectric button which has a smaller upper portion adapted to fit in said recess. 
     
     
       15. A disposable attachment element for securing a microwave antenna element to skin of a patient to receive microwave radiation from the patient during injection of liquid into a blood vessel, the element comprising a flexible carrier sheet having an adhesive undersurface, a button of dielectric material on an upper surface of the sheet, and the sheet having an adhesive upper surface portion surrounding the button to receive a peripheral portion of a microwave antenna element coupled to the attachment element with the button received in a corresponding recess of the antenna element. 
     
     
       16. An attachment element as claimed in claim 15, further including an elongate measuring scale element releasably attachable to the button for locating the button on a patient's skin relative to the tip of an injection cannula inserted into a blood vessel. 
     
     
       17. A disposable attachment element for securing a microwave antenna element to skin of a patient to receive microwave radiation from the patient during injection of liquid int a blood vessel, the element comprising a flexible carrier sheet having an adhesive undersurface, a button of dielectric material on an upper surface of the sheet, and the sheet having an adhesive upper surface portion surrounding the button to receive a peripheral portion of a microwave antenna element coupled to the attachment element with the button receive in a corresponding recess of the antenna element, wherein the button has a stepped configuration with a larger base portion and smaller upper portion. 
     
     
       18. An attachment element as claimed in claim 17, wherein the carrier element includes an extension portion surrounding said upper surface portion with a flexible conformal covering layer over said extension portion. 
     
     
       19. An attachment element as claimed in claim 18, wherein the extension portion has a circular configuration with at least one radially outwardly extending leg. 
     
     
       20. An attachment as claimed in claim 19, wherein said leg is provided with a lengthwise measuring scale for locating the button on a patient's skin relative to the tip of an injection cannula inserted into a blood vessel. 
     
     
       21. A method of monitoring electromagnetic microwave emission from a patient during injection of liquid into a blood vessel to detect extravasation of the liquid comprising providing an electromagnetic microwave detection system including microwave antenna means having a reusable microwave antenna element connected with processing means for responding to changes of microwave emission from the patient representative of extravasation, and a disposable attachment element for securing the antenna element to the patient's skin by means of male and female coupling elements on the attachment element and the antenna element respectively, adhesively securing the attachment element to the patient's skin over an injection site, coupling the antenna element to the attachment element to form the antenna means, using the antenna means to monitor for extravasation during injection of the liquid, uncoupling the antenna element from the attachment element after injection for reuse of the antenna element, and removing the attachment element from the patient's skin for disposal. 
     
     
       22. A method of monitoring electromagnetic microwave emission from a patient during injection of liquid into a blood vessel to detect extravasation of the liquid comprising providing an electromagnetic microwave detection system including microwave antenna means having a reusable microwave antenna element connected with processing means for responding to changes of microwave emission from the patient representative of extravasation, and a disposable attachment element for securing the antenna element to the patient's skin by means of male and female coupling elements on the attachment element and the antenna element respectively, adhesively securing the attachment element to the patient's skin over an injection site, coupling the antenna element to the attachment element to form the antenna means, using the antenna means to monitor for extravasation during injection of the liquid, uncoupling the antenna element form the attachment element after injection for reuse of the antenna element, and removing the attachment element from the patient's skin for disposal, further including the steps of providing the attachment element with a linear measuring scale prior to securing the attachment element to the patient's skin, and using the measuring scale to relate the position of the attachment element relative to a cannula inserted into the blood vessel for performing the liquid injection.